Indeed, it is the absence of a preference. Each discrete sensual act conforms to one of the two primary orientations, we don't need a whole new "catch-all" term to collect all the people who simply have a hard time making decisions. If you like pepperoni but you're also fine with Hawaiian, we don't have a word to describe people in their moment of indecision while talking to the pizza guy.
I'm disappointed in you people. I've pried open a portal into wholly new domains of erotica, and all you can think about is the proper nomenclature for your provincial, terran sex acts. Think about intelligent planets having sex with each other, or amorous universes entwined through parallel eternities.
(CW)TB